This invention relates to electrical devices impregnated with a dielectric fluid, that is substantially free from water, having a high unsaturation level and a low viscosity. This dielectric fluid is a reaction product of a siloxane and a silane.
The silane has the general formula of R.sub.a R'.sub.b Si(OX).sub.4-a-b wherein R is selected from the group consisting of hydrogen substituted saturated hydrocarbon radicals, and unsubstituted saturated hydrocarbon radicals, R' is selected from the group consisting of substituted and unsubstituted unsaturated hydrocarbon radicals, X is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, and acyl radicals, a has a value of 0 to 3, b has a value of 0 to 3, with a+b having a value of 0 to 3.
In numerous electrical devices, such as transformers, cables, capacitors, switches, fuses, reactors, regulators, circuit breakers, and similar equipment, it is necessary to provide a liquid insulating medium which is called a "dielectric fluid". This liquid has a substantially higher breakdown strength than air and by displacing air from spaces between conductors in the electrical apparatus, materially raises the breakdown voltage of the electrical device. With the ever increasing sophistication of electrical equipment, the various electrical devices are operating at higher and higher voltages. This means that the dielectric fluids used in such devices are subjected to greater and greater stresses. These problems have, of course, necessitated the search for improved dielectric fluids.
Over the years a wide variety of fluids have been used as dielectric fluids in various kinds of electrical devices. By way of example one might mention the classes of mineral oils, askarels, vegetable oils, organic esters, polyhydrocarbon oils, fluorinated liquids, and silicone liquids. As one might surmise from the foregoing host of materials which have been used as dielectric fluids, no one fluid is ideal or solves all of the industries needs.
It has been discovered in accordance with this invention that when a dielectric fluid, that is substantially free from water, which is a reaction product of a siloxane and silane, having a high unsaturation level and a low viscosity, is used to impregnate electrical devices, that not only are good physical and electrical properties obtained, but enhanced flammability characteristics can be achieved. The silane has the general formula R.sub.a R'.sub.b Si(OX).sub.4-a-b wherein R is selected from the group consisting of hydrogen, substituted saturated hydrocarbon radicals, and unsubstituted saturated hydrocarbon radicals, R' is selected from the group consisting of substituted and unsubstituted unsaturated hydrocarbon radicals, X is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, and acyl radicals, a has a value of 0 to 3, b has a value of 0 to 3, with a+b having a value of 0 to 3.
It is thus an object of this invention to provide electrical devices impregnated with said dielectric fluid.